You are here:

Knowledge Base

This Knowledge Base is intended to provide answers to some frequently asked questions and give you some useful tips for using your Hamilton Medical ventilator. If you can't find the information you're looking for here, feel free to mail us with your query.

Most ventilator manufacturers use their own specific abbreviations for the different ventilation modes on their ventilators. It is important for users to have a tool that enables them to compare the modes of one manufacturer with the modes of another.

In the presence of dynamic pulmonary hyperinflation, the average end-expiratory pressure inside the alveoli (i.e., the actual, total PEEP (PEEPtot)) is higher than the PEEP applied by the ventilator (PEEPe). The difference between PEEPtot and PEEPe corresponds with the intrinsic PEEP (PEEPi), and is also known as AutoPEEP (1).

During the expiratory phase of ventilation, the exhaled gas exits the ETT and is measured proximally at the flow sensor. Where a leak is present, the exhaled tidal volume (VTE) is significantly less than the inhaled tidal volume (VTI). In Adaptive Pressure Ventilation (APV) mode, the HAMILTON-G5 must therefore deliver a higher pressure and potentially a larger VTI to compensate for the leak in order to achieve a tidal volume close to the set exhaled volume target (VTarget).

INTELLiVENT®-ASV® uses partial pressure of end tidal CO2 (PetCO2) measured by the CO2 sensor as monitoring input for the regulation of ventilation. The measured PetCO2 value is used to track partial CO2 pressure in the arteries (PaCO2).

In conventional ventilation modes, the clinician sets ventilator controls such as tidal volume, respiratory rate, and expiratory and inspiratory time to achieve clinical targets, including a certain level of oxygenation and alveolar ventilation for the patient.

One of the greatest challenges when mechanically ventilating patients is finding the correct setting for positive end-expiratory pressure (PEEP). This task can be made easier by using transpulmonary pressure measurement to distinguish between the pressure in the lungs and the chest wall components.

By knowing how CO2 behaves on its way from the bloodstream through the alveoli to the ambient air, you can obtain useful information about ventilation and perfusion. Monitoring the CO2 level during respiration (capnography) is noninvasive, easy to do, and relatively inexpensive.

Optimal patient-ventilator synchrony is of prime importance, as asynchronies lead to increased work of breathing and patient discomfort, and are also associated with higher mortality and prolonged mechanical ventilation (1, 2, 3).

High flow oxygen therapy combines several physiological effects: Oxygenation, PEEP, an increase in the end-expiratory lung volume (EELV), a lower respiratory rate (RR), a decrease in intrinsic PEEP and work of breathing, lower PaCO2, and improved humidification and comfort (1, 2). The optimal flow setting depends on the indications and the desired physiological effect.

Airway driving pressure is associated with clinical outcomes in ARDS, post-surgical, and normal-lung patients, and is a measure of the strain applied to the respiratory system and the risk of ventilator-induced lung injuries. Evidence suggests we should keep driving pressure below 14 cmH2O. But how can we measure it?

The American Thoracic Society and the American College of Chest Physicians recently provided recommendations to help optimize liberation from mechanical ventilation in adult ICU patients (1). They suggest using a ventilator liberation protocol and performing spontaneous breathing trials (SBTs) with modest inspiratory pressure support (5-8 cmH2O). So how do we implement these recommendations using the Adaptive Support Ventilation (ASV) mode?